title: Stoichiometry of SecYEG in the active translocase of Escherichia coli varies with precursor species.
abstract: We have established a reconstitution system for the translocon SecYEG in proteoliposomes in which 55% of the accessible translocons are active. This level corresponds to the fraction of translocons that are active in vitro when assessed in their native environment of cytoplasmic membrane vesicles. Assays using these robust reconstituted proteoliposomes and cytoplasmic membrane vesicles have revealed that the number of SecYEG units involved in an active translocase depends on the precursor undergoing transfer. The active translocase for the precursor of periplasmic galactose-binding protein contains twice the number of heterotrimeric units of SecYEG as does that for the precursor of outer membrane protein A.
authors.affiliation: Department of Biochemistry, University of Missouri, Columbia, MO 65211, USA.
authors.forename: Chunfeng
authors.initials: C
authors.lastname: Mao
authors.forename: Carl E
authors.initials: CE
authors.lastname: Cheadle
authors.forename: Simon J S
authors.initials: SJ
authors.lastname: Hardy
authors.forename: Angela A
authors.initials: AA
authors.lastname: Lilly
authors.forename: Yuying
authors.initials: Y
authors.lastname: Suo
authors.forename: Raghavendar Reddy
authors.initials: RR
authors.lastname: Sanganna Gari
authors.forename: Gavin M
authors.initials: GM
authors.lastname: King
authors.forename: Linda L
authors.initials: LL
authors.lastname: Randall
mesh_terms: D002135:Calcium-Binding Proteins / Q000378:metabolism*; D002250:Carbon Radioisotopes / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology*; D029968:Escherichia coli Proteins / Q000235:genetics* / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D018625:Microscopy, Atomic Force; D009004:Monosaccharide Transport Proteins / Q000378:metabolism*; D033902:Periplasmic Binding Proteins / Q000378:metabolism*; D011510:Proteolipids / Q000378:metabolism; D000069816:SEC Translocation Channels; D013462:Sulfur Radioisotopes / Q000378:metabolism; D022161:Transport Vesicles / Q000378:metabolism
chemical_list: D002135:Calcium-Binding Proteins; D002250:Carbon Radioisotopes; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D009004:Monosaccharide Transport Proteins; D033902:Periplasmic Binding Proteins; D011510:Proteolipids; D000069816:SEC Translocation Channels; D013462:Sulfur Radioisotopes; C023550:galactose-binding protein; C020485:proteoliposomes
keywords: SecA; SecB; export; secretion